Bezel setting
A setting in which a thin rim of metal surrounds the stone's girdle and holds it in place.
Full and partial bezels
A full bezel surrounds the entire girdle. A half bezel covers two sides and leaves the others open for more light and a lighter look. Bezels suit round, oval, pear and emerald cuts, and they are the usual choice for cabochons, which have no facets for prongs to grip.
Pros and cons
Bezels protect the girdle and the pavilion from knocks, and they do not snag on clothing. The trade-off is that metal covers part of the stone, so a bezel set diamond can look slightly smaller and receive a little less light than the same stone in prongs.
Rendering bezels
The polished bezel wall acts like a curved mirror around the stone, so it reflects the environment strongly. A clean studio environment with soft light panels gives a crisp rim, while a busy environment makes the edge look noisy.
Check the CAD for a gap or an overlap between the bezel and the stone. In close-ups, a stone that floats above its seat or cuts through the wall is easy to spot. Bezel rings also benefit from a side view that shows the height of the cup and any gallery detail below it.
Yellow gold bezels around white diamonds reflect warm colour into the stone. That is real optics, and removing it in a render would make the image less accurate.